User guide

3.1. MANIFEST CONSTANTS 41
scb
id CIN:y, POS:y, NAT:n
This SCB field holds one of the values id
inscb, id outscb or id inoutscb, indi-
cating whether the stream is for input, output or both.
scb
lblock CIN:y, POS:y, NAT:n
This SCB field holds the number of last block. The first block of a stream is
numbered zero.
scb
ldata CIN:y, POS:y, NAT:n
This SCB field holds the number of bytes in the last block of a stream.
scb
pos CIN:y, POS:y, NAT:n
This SCB field points to the position within the buffer of the next character to be
transferred. This field is updated every time a character is transferred to or from a
stream.
scb rdfn CIN:y, POS:y, NAT:n
This SCB field is zero if the stre am cannot perform input, otherwise it is the
function to refill (or replenish) the buffer with more characters. It is given the SCB as
its argument and returns TRUE if it successfully replenishes the buffer with at least one
character. It otherwise retur ns FALSE setting result2 to -1 if the end of file has been
encountered, -2 if there was a timeout before any character were read, -3 no character
was available in polling mode. Any other value in result2 is and error code.
scb
reclen CIN:y, POS:y, NAT:n
A file is normally regarded as a potentially huge sequence of bytes, but can also be
treated as a sequence of fixed length records. The reclen SCB field hold the length
in bytes of such records. The first record of a file has number zero. Unless the lengt h
of a file is a multiple of the record length, the length of last record of a file wil l be too
short.
scb
size CIN:y, POS:y, NAT:n
This constant is equal to the number of words in a stream control block.
scb
timeout CIN:y, POS:y, NAT:n
This SCB field holds the stream timeout value for TCP streams. If it is zero no
timeout is applied. If it is negative, data is only tranferred if it is immediately available.
If it is strictly positive it represents a t i me out value in mill i -se c onds.
scb timeoutact CIN:y, POS:y, NAT:n
This SCB field controls the effect of a time out on this stream while reading using
rdch. A value of 0 causes the time out to be ignored, a val ue of -1 caused the rdch to
return with the value endstreamch, and a value of -2 causes rdch to return with the
value timeoutch.
scb
type CIN:y, POS:y, NAT:n
This SCB field holds the type of the stream which will be one of the following: